Cerebral sympatholysis: experiments on in vivo cerebrovascular regulation and ex vivo cerebral vasomotor control
Date
2023-10-19
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0009-0003-0201-0528
Type
Thesis
Degree Level
Masters
Abstract
Whether cerebral sympathetic-mediated vasomotor control can be modulated by local brain metabolism remains unknown. This study tested the hypothesis that application or removal of a cognitive task during a cold pressor test (CPT) would attenuate and restore rises in cerebrovascular resistance (CVR), respectively. Middle cerebral artery blood velocity (transcranial Doppler) and mean arterial pressure (finger photoplethysmography) were examined in healthy adults (n=16; 8 F and 8 M) who completed a control CPT, followed by a CPT coupled with a cognitive task administered either A) at the onset of the CPT and terminated 30 s prior to the end of the CPT or B) 30 s after the onset of the CPT and for the duration of the CPT (condition order was counterbalanced). The major finding was that the CPT increased the index of CVR, and such increases were abolished when a cognitive task was completed concurrently and restored when the cognitive task was removed. As a secondary experiment, vasomotor interactions between sympathetic transduction pathways (α1 adrenergic and Y1 peptidergic) and compounds implicated in functional sympatholysis (adenosine (ADO), and adenosine triphosphate (ATP)) were explored in isolated porcine cerebral arteries (wire myography). The data reveal α1 receptor agonism potentiated vasorelaxation modestly in response to ADO but not ATP. Pre-exposure to ATP attenuated contractile responses to α1 agonism. Overall, the data suggest a cognitive task attenuates increases in CVR during sympatho-excitation, possibly related to an interaction between purinergic and α1-adrenergic signaling pathways.
Description
Keywords
sympatholysis, sympathetic, adrenergic, cerebrovascular, cognition, brain
Citation
Degree
Master of Science (M.Sc.)
Department
Kinesiology
Program
Kinesiology